/usr/include/gf2x/gf2x_mul4.h is in libgf2x-dev 1.2-5.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 | /* This file is part of the gf2x library.
Copyright 2007, 2008, 2009, 2010, 2013, 2015
Richard Brent, Pierrick Gaudry, Emmanuel Thome', Paul Zimmermann
This program is free software; you can redistribute it and/or modify it
under the terms of either:
- If the archive contains a file named toom-gpl.c (not a trivial
placeholder), the GNU General Public License as published by the Free
Software Foundation; either version 3 of the License, or (at your
option) any later version.
- If the archive contains a file named toom-gpl.c which is a trivial
placeholder, the GNU Lesser General Public License as published by
the Free Software Foundation; either version 2.1 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful, but WITHOUT
ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
FITNESS FOR A PARTICULAR PURPOSE. See the license text for more details.
You should have received a copy of the GNU General Public License as
well as the GNU Lesser General Public License along with this program;
see the files COPYING and COPYING.LIB. If not, write to the Free
Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
02110-1301, USA.
*/
#ifndef GF2X_MUL4_H_
#define GF2X_MUL4_H_
#include "gf2x.h"
/* All gf2x source files for lowlevel functions must include gf2x-small.h
* This is mandatory for the tuning mechanism. */
#include "gf2x/gf2x-small.h"
/* specialized Karatsuba */
GF2X_STORAGE_CLASS_mul4
void gf2x_mul4 (unsigned long *c, const unsigned long *a, const unsigned long *b)
{
unsigned long aa[2], bb[2], ab[4];
unsigned long lo[4], hi[4];
gf2x_mul2 (lo, a, b);
gf2x_mul2 (hi, a + 2, b + 2);
aa[0] = a[0] ^ a[2];
aa[1] = a[1] ^ a[3];
bb[0] = b[0] ^ b[2];
bb[1] = b[1] ^ b[3];
unsigned long c24 = lo[2] ^ hi[0];
unsigned long c35 = lo[3] ^ hi[1];
gf2x_mul2 (ab, aa, bb);
c[0] = lo[0];
c[1] = lo[1];
c[2] = ab[0] ^ lo[0] ^ c24;
c[3] = ab[1] ^ lo[1] ^ c35;
c[4] = ab[2] ^ hi[2] ^ c24;
c[5] = ab[3] ^ hi[3] ^ c35;
c[6] = hi[2];
c[7] = hi[3];
}
#endif /* GF2X_MUL4_H_ */
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